从不同嵌套的哈希中提取特定键

Question

我正在尝试将提供的哈希中的不同 "Name" 值连接成一个字符串。所以输出应该是一个包含所有 "Name" 值的数组或字符串。

对我来说困难在于 嵌套级别在两个和四个 parents 之间变化 parents。

我试过用两种方法解决：

递归地遍历散列并在每个级别上将值附加到数组。终于把数组吐出来了
展平哈希，然后从该数组中挑选

不幸的是，none 相关问题中给出的答案似乎也有效。我敢肯定这很简单，但我似乎无法弄清楚。非常感谢

my_hash = { "BreadCrumbs" => {
                    "Id" => 375,
                    "Name" => "Willingen",
                    "Parent" => {
                        "Id" => 52272,
                        "Name" => "Wintersport-Arena Sauerland",
                        "Parent" => {
                            "Id" => 8, 
                            "Name" => "Germany"
                        }
                    }
                }
            }

Answer 1

▶ hash = { "BreadCrumbs" => {
▷     "Id" => 375,        
▷     "Name" => "Willingen",        
▷     "Parent" => {        
▷       "Id" => 52272,            
▷       "Name" => "Wintersport-Arena Sauerland",            
▷       "Parent" => {            
▷         "Id" => 8,                 
▷         "Name" => "Germany"                
▷       }              
▷     }          
▷ }} 
▶ def concat hash
▷   [hash['Name'], hash['Parent'] ? concat(hash['Parent']) : nil]
▷ end  
▶ (concat hash['BreadCrumbs']).flatten.compact
#⇒ ["Willingen", "Wintersport-Arena Sauerland", "Germany"]

我不会在每次迭代时都展平，因此结果仍然包含层次结构：

▶ concat hash['BreadCrumbs']
#⇒ ["Willingen", ["Wintersport-Arena Sauerland", ["Germany", nil]]]

请求的字符串作为结果：

▶ (concat hash['BreadCrumbs']).flatten.compact.join ', '
#⇒ "Willingen, Wintersport-Arena Sauerland, Germany"

Answer 2

对于任意数量的级别，不使用递归：

def pull_names(hash)
  h = hash
  names = []
  loop do
    names << h["Name"]
    return names unless h.key?("Parent")
    h = h["Parent"]
  end
end

假设：

hash = { "BreadCrumbs" => {
           "Name" => "Willingen",        
           "Parent" => {        
             "Id" => 52272,            
             "Name" => "Wintersport-Arena Sauerland",            
             "Parent" => {            
               "Id" => 8,                 
               "Name" => "Germany",
               "Parent" => {            
                 "Id" => 1,                 
                 "Name" => "Bora Bora"
               }              
             }          
           }
         }
       }

然后：

arr = pull_names hash["BreadCrumbs"]
  #=> ["Willingen", "Wintersport-Arena Sauerland", "Germany", "Bora Bora"] 
arr.join(' ')
  #=> "Willingen Wintersport-Arena Sauerland Germany Bora Bora"

从不同嵌套的哈希中提取特定键

Extract specific keys from variedly nested hash

ruby

recursion

hash

nested

extract